The need to improve the skills of primary care workers in the management of mild-to-moderate mental health problems in children and adolescents is widely recognized. One model for providing such skills is the use of specialist psychiatric nurses as interface workers in a consultation–liaison role. This aims to provide training and expert advice to facilitate the detection, assessment and management of child and adolescent mental health problems. The objective of this study is to assess the impact of a pilot scheme which placed three consultation–liaison interface workers, for 15% of their time, in primary care. This study involved a qualitative assessment of health professionals' experiences of the new system, using constant comparison analysis of the transcribed texts of five focus groups. The setting was within the participating surgeries and at the secondary care centre. The participants comprised ten secondary care workers, ten GPs, seven health visitors and three school nurses. The main outcome measure was the views of the health care professionals of the interface worker service. The results showed that primary care staff reported strong, positive effects on confidence, morale and patient care, although a few possible problems were perceived in terms of carers' understanding of brief intervention. Prior to the introduction of the new system, they felt they had little to offer children and adolescents with mental health problems, but now they had a service to offer. The interface workers had particularly enhanced their treatment skills/options. However, the secondary care workers felt that there had been little effect on their workload although only four out of 54 practices feeding into them had had interface workers appointed. Although they recognized the potential benefits for mild to moderate cases in primary care, they were also concerned that scarce resources might be being directed towards lower priority cases. This pilot study concluded that this was an efficient, effective service offering a quick response to patients, equipping primary care workers with treatment skills and having a positive effect on the numbers of referrals to secondary care. Further, more extensive quantitative work is needed to find out if these conclusions are really justified.